The impact of cognitive reserve on the effectiveness of balance rehabilitation in Parkinson's disease

BACKGROUND: Cognitive reserve (CR) can be considered an active expression of brain resilience in response to damage. Several studies have shown the influence of CR on cognitive impairment and its relationship with cognitive function in Parkinson's disease (PD). AIM: To show if CR influences the effectiveness of balance rehabilitation in PD patients who performed a conventional rehabilitative treatment. DESIGN: Observational longitudinal study. SETTING: Neurology outpatient Unit, University Hospital. POPULATION: Fifty-three patients affected by idiopathic PD, stage 2-3 at the Hoehn and Yahr scale. METHODS: Each patient underwent 32 group sessions of conventional rehabilitative treatment. At baseline, patient CR was assessed by the Cognitive Reserve Index questionnaire (CRIq). The primary outcome was the evaluation of static and dynamic balance modifications, induced by the treatment, through the Berg Balance Scale (BBS), assessed at T0 and T1. Mini Mental State Examination, Unified Parkinson's Disease Rating Scale Part III (clinician-scored monitored motor evaluation) and Brief Intelligence Test were assessed only at T0 and used as descriptive variables. RESULTS: Considering the clinically meaningful change, BBS improved in 26% of patients worsened in 2% and was unchanged in 72%. BBS score significantly improved in older patients, and in those with lower CRI total score. A significant inverse correlation was observed between changes in BBS and work and education related CR. Patients with lower baseline BBS score showed more improvement in balance. CONCLUSIONS: We found an inverse correlation between CR level and balance improvement in PD patients who underwent conventional rehabilitation: higher improvement in BBS was observed in those with a lower CRI score. This may suggest that patients with higher CRI could benefit from more stimulating modes of non conventional rehabilitation (e.g. robotic, virtual reality). CLINICAL REHABILITATION IMPACT: Rehabilitation should be individually tailored with CR considered as a significant variable.